The structure of quetiapine, 2-(2-(4-dibenzo[b,f]-[1,4]thiazepin-11-yl-1-piperazinyl)ethoxy)ethanol, is shown below (I).

Quetiapine is a psychoactive organic compound that is an antagonist for multiple neurotransmitter receptors in the brain. Merck Index, 13th Ed., 8130 (2001). Quetiapine is an antipsychotic agent useful for treating, among other things, schizophrenia. Quetiapine can be made, for example, as taught in U.S. Pat. No. 4,879,288, incorporated in its entirety herein by reference.
As taught in the '288 patent, quetiapine can be made via reaction of 11-piperazinyl dibenzo[b,f]-[1,4]thiazepine hydrochloride and 2-(2-chloroethoxy)ethanol in a solvent. Reaction times are long (e.g. 24 hours). Also, starting materials such as the 11-piperazinyl dibenzo[b,f]-[1,4]thiazepine are undesired in the product and can be difficult to remove from the product.
There is a need for an improved process for making quetiapine from 11-piperazinyl dibenzo[b,f]-[1,4]thiazepine allowing shorter reaction times and affording a quetiapine product that contains a lower level of impurities (such as the unreacted starting material).